Method of and material for preventing metal from corroding



Patented as 19.1933.

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4 This invention relates to the art of preventing metal from .corrodmg and has to do with a self-cleaning paint-like material or .coating adapted for finishing fabricated metal, and according to my invention this is done by the application and heating of anadmixtureadapted, uponthe' application of heat, to liberate both cleaning acid, and a substance with which and with the metal the liberated acid chemically reacts, forming a protective finish which remainson the metal.

Other objects of the invention are: to overcome the necessity of preparing metal for painting; to reduce the cost of painting metal; to reduce the number of operations required in painting 'metalyto improve the quality of painted finishes; to increase the life of painted finishes and. to generally 1mprove the art of preventing metals from corroding.

The invention comprises the improvements to befpresently described and finally claimed and generally stated it consists in forming a protective coating'on metal, particularly steel, by applying an admixture comprising a thermally decomposable phosphate and a neutralizer for phosphoric acid, to the metal, then heating the metal to l1berate phosphoric acid and permit it to attack the neutralizer and the metal to' form the protective coating.

The thermally decomposable phosphate may be an inorganic one like ammonium 4.3 phosphate, or an organic one like aniline phosphate and the neutralizer for phosphoric acid may be any suitable material for accomplishing my purposes, but Iprefer a water insoluble metallic oxide such as the oxide of manganese, magnesium, zincor iron; or it may 1 Application flied February '4, 19am Serial 1%. 425,822.

be finely divided metal such as iron, aluminum or zinc. Of course these neutralizers may be used individually or collectively. In the following specification I will select dianiline phosphate asthe decomposable phosphate, and iron oxide (Fe O as the neutral izer for phosphoric acid as I find these materials produce satisfactory commercial admixturesalthough it should be understood that other materials may be used without departing from my invention.

To produce a satisfactory material I may use 4 Dianiline phosphate L 6.44 pounds Iron oxide (F6203) 1.60 pounds .Both ingredients are finely divided and thoroughly admixed and may be applied to the metal as a dusting powder. If the metal is first heated to a-suliicient temperature to melt the aniline phosphate, adhesion of the powder to the metal is immediately secured and a more even coating obtained. Or water may be added to the powder to form a paste or more water may be added to form a material .of paint-like constituency. Other'vehicles besides the water may be employed i desired, such as denatured, ethyl, methyl, butyl, propal alcohol;fhydrocarbon oils or solvents; paints or varnishes.

A very satisfactory material is made by dissolving varnish gums'su'ch as gils'onite and stearine pitch in kerosene to form a varnish and then admixingit with the above described powder -to form a paint-like product having the following composition:

Dianiline phosphate 6.44 pounds Iron oxide (Fe O 1.60 pounds Kerosene 6.87 gallons Stearine pitch 8.69 pounds Gilsonite ..a 9.81 pounds It is well to thoroughly grind the admixture in a suitable paint mill and themsieve or centrifuge out all undesired-specks to insurea finished coatingon' the metal free from objectionable blemishes.

Before applying this admixture to the metal as, for instance, a sheet steel automobile fender, it is well to free it from extrabrushing s am in" or di in. and after the coated metal has been permitted to drain and air dry for a short time, say approximately ten minutes, it is placed in an oven heated sufiiciently to decompose the aniline phosphate, and kept there suiiiciently long to complete the chemical action between the liberated phosphoric acid and the iron' oxide 1 and the metal. In practice, I have found that a. temperature of 450 F. for a period ofv 30 minutes produces satisfactory results.

The coating on steel produced by the above admixture, used as described, is darkred, or, black, has a glossy appearance, has suiiieient hardness to resist scratching with the finger nail, is flexible enough to Withstand sharp bends and shows great resistance to corrosion when subjected to humidity or salt spray tests.

If desired, one or more coats of paint, lacquer, varnish, or japan may be applied over the prime coating described, for decoration or to augment the resistance to corrosion.

I claim:

1. A material for preventing metal from corroding being an admixture of a material adapted tolibera-te phosphoric acid upon the application of heat and a neutralizer for phosphoric acid.

2. A material for preventing metalfrom corroding, being an admixture comprising a thermally decomposable phosphate and a neutralizer' for phosphoric acid.

3. A material for preventing metal from 9 corroding being an admixture comprising a thermally decomposable phosphate, a neutralizer for phosphoric acid and a vehicle.

4. A material for preventing metal from corroding, being an admixture comprising a thermally decomposable. phosphate, a neutralizer for phosphoric acid, a vehicle and'a varnish gum. v

5. A material for preventing metal from corroding, being an admixture comprising aniline phosphate, a neutralizer for phosphoric acid, a vehicle and a varnish gum.

6. A material for preventing metal from corroding, being an admixture comprising a thermally decomposable phosphate, iron oxide, a vehicle and a varnish gum.

7 A material for preventing metal from corrodmg, being an admlxture comprlslng a thermally decomposable phosphate, a neutralizer for phosphoric acid, a liquid hydro- 9 carbon and a varnish gum.

8. A material for preventing metal from corroding, being an admixture comprising a thermally decomposable phosphate, :1. neutralizer for phosphoric acid, a vehicle and stearine pitch.

9. A material for preventing metal from corroding, being an admixture comprising aniline phosphate, iron oxide, a liquid bydrocarbon and stearine pitch.

10. The method of preventing metal from corroding, comprising applying to said metal an admixture comprising a material adapted to liberate phosphoric acid upon the application of heat and aheutralizer for phosphoric acid, and heating the coating to liberate phosphoric acid and permit it to combine With the said neutralizer and the said metal, to form a protective coating for the said metal.

11. The method of preventing metal from corroding, comprising applying to the said metal an admixture comprising a thermally decomposable phosphate and a neutralizer for phosphoric acid, and heating the coated metal to liberatephosphoric acid and permit it to combine with-the said neutralizer and the said metal, to form a protective coating for the said metal.

12. The method'of preventing metal 'from corroding, comprising applying to the said metal an admixture comprising aniline phosphate and a neutralizer for phosphoric acid, and heating the coated metal to liberate phosphoric acid and permit it to combine with the said neutralizer and the said metal to form a protective coating for the said metaL.

13. The method of preventing metal ,from corroding, comprising applying to the said metal an admixture comprising a thermally decomposable phosphate and iron oxide, and heating the coated metal to liberate phosphoric acid and permit it to combine with the said iron oxide and the said metal to form a protective coating for the said metal.

14. The method of preventing metal from corroding, comprising applying to the said metal an admixture comprising aniline phosphate and iron oxide, and heating the coated. metal to liberate phosphoric acid and permit it to combine with the said ironoxide and the said metal to form a protective coating for the said metal. 7

JAMES H. GRAVELL. 

